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Photonics Crystals, Optical-Induced Lattices and Solitons

Prof. Wieslaw Krolikowski; Prof. Yuri Kivshar at Nonlinear Physics Centre

Photonics Crystal

Photonic crystals are usually viewed as an optical analog of semiconductors that modify the properties of light similarly to a microscopic atomic lattice that creates a semiconductor band-gap for electrons. It is therefore believed that by replacing relatively slow electrons with photons as the carriers of information, the speed and band-width of advanced communication systems will be dramatically increased, thus revolutionizing the telecommunication industry. However, to employ the high-technology potential of photonic crystals, it is crucially important to achieve a dynamical tunability of their properties. This idea can be realized by changing the light intensity in the nonlinear photonic crystals.

Optically-Induced lattices

Nonlinear propagation of waves in periodic media has long been a focus of strong interest. The physics of this phenomenon is common for a variety of systems, including excitations in biological molecules, electrons in solid-state matter, ultracold atoms in optical standing waves, and light waves in nonlinear media with periodic modulation of the refractive index. Only in optics, however, the effects associated with this phenomenon can be directly observed and examined in close details. A strong motivation for work in this area comes from the analogy between the behaviour of light in periodic photonic structures and electrons in superconductors. This analogy suggests the possibility of replacing electronic components with novel types of photonic devices where light propagation is fully controlled in engineered micro-structures. Nonlinearity adds a possibility to control propagation of light purely optically, i.e. with light itself. Such all-optical devices may form foundation of future high-bandwidth, ultrafast communications and computing technologies.

Solitons and Their Interactions

One of the most important research highlights of 2000 is the prediction of a new object in the nonlinear physics, a dipole-mode vector soliton. This is a composite optical beam that carries a dipole momentum and can be understood either as a Hermite-Gaussian guided mode trapped by a soliton-induced waveguide or as a bound state of two simpler solitary waves in a bulk medium, the so-called "molecule of light". This and other, more complicated and intriguing objects have been predicted and demonstrated experimentally (in collaboration with a team of the Laser Physics Centre), including quadrupole vector solitons and "necklace" beams. This topic attracted a great interest of other groups with almost simultaneous experimental verifications done at Princeton (USA) and Technion (Israel). Our results gained several invitations for the major research meetings in optics (Nonlinear Optics OSA Topical Meeting, OSA Annual Meeting, SPIE Symposium on Beam and Pulse Propagation, NATO Summer School, etc), and were also presented as a post-deadline paper at CLEO/Europe (Nice).